1. Field of the Invention
The present invention relates to a biasing arrangement for a pawl of a reversible ratchet-type wrench to provide reliable ratcheting. The present invention also relates to an improved head structure for a ratchet-type wrench to lower the manufacture cost.
2. Description of the Related Art
U.S. Pat. No. 2,957,377 issued to Hare on Oct. 25, 1960 discloses a reversible ratchet type wrench comprising a body 10 having a handle 11 and a head 12. A cap 39 and an annular wall 44 are provided to upper side and lower side of the head 12, respectively. Yet, this increases the assembly time and the manufacture cost and adversely affects the appearance. A shifting lever 35 is retained in place by a spring 33 that is located in a cylindrical opening 34. Nevertheless, formation of the cylindrical opening 34 that extends upward at an incline is relatively difficult. In addition, formation of the cavity 16 having converging straight sides 17, 18 which diverge in the direction of the periphery of rotatable member 14 requires expensive and accurate computer-numeric-control (CNC), which further results in an increase in the cost together with a low production rate. This is why such a reversible ratchet type wrench is hardly seen in the market.
FIGS. 10 and 11 illustrate another conventional ratchet type wrench comprising a handle 12' and a head 11'. The head 11' is machined to form four consecutive compartments for receiving the drive member 20', the pawl 30' and the shifting lever 40', wherein three of the compartments can be formed by cutting, yet the remaining one must be machined by CNC. Further, the resultant head structure is relatively weak and thus has a poor torque-bearing capacity. In addition, the movement of the pawl 30' for changing ratcheting direction is found unreliable, as it is achieved via transmission of the hook end 442' of a spring 44' attached to the shifting lever 40'.